Opioid dependence continues to be a serious public health problem, particularly with the dramatic rise in prescription opioid abuse. Traditional methods of detoxification from opioids, including tapering off the opioid agonist methadone or buprenorphine (BUP) and supportive treatment of symptomatology with the alpha2- adrenergic receptor agonists are limited by the high relapse rate and/or lack of efficacy in relieving subjective symptoms. In addition, transitioning individuals from methadone to BUP maintenance has been limited by the need to drastically taper the methadone maintenance dose of methadone-maintained individuals prior to switching to BUP maintenance, which can precipitate opiate withdrawal and relapse. This application takes a novel approach to address the problem of opioid withdrawal by examining the utility of the L-type calcium channel blocker (CCB) isradipine as an adjunct to BUP detoxification. L-type CCBs have been shown to alleviate opioid withdrawal in opioid-treated nonhumans, to be safe and effective in alleviating withdrawal symptoms in human detoxification trials, and to have low abuse potential. Moreover, isradipine was the most effective of several CCBs tested and was more effective than the alpha2-adrenergic agonist clonidine in blocking naloxone-induced behavioral effects without producing self-reported effects associated with high potential for abuse. Thus, this project will address the need for improved detoxification strategies by assessing the tolerability and preliminary efficacy of adjunct isradipine during a BUP detoxification in opioid-dependent participants. The aim of this 8-week randomized, placebo-controlled pilot clinical trial is to determine the potential utiliy of the L-type CCB isradipine to improve treatment outcomes in up to 60 opioid-dependent individuals undergoing a BUP detoxification procedure. The specific aims are to (Aim 1) determine the efficacy of isradipine to reduce withdrawal symptoms, craving, and illicit use of opioids in opioid-dependent individuals undergoing BUP detoxification and (Aim 2) determine the tolerability and safety of controlled-release isradipine (10 mg/day) in opioid-dependent individuals undergoing BUP detoxification. Currently, the only FDA-approved medications for opioid withdrawal are the opioid agonist's methadone and BUP, both of which have abuse liability. Our findings, if positive, will support a larger phase II clinical trial. Ultimately, ths work could impact the addiction field by providing another pharmacological tool that is efficacious for treating opioid withdrawal while having minimal abuse liability. This would shift clinical practice establishing an effective adjunct regimen for BUP detoxification as well as having the potential to enhance transition to naltrexone therapy.